摘要目的 探讨我国多个地区宋内志贺菌的同源性与整合子介导其耐药的机制.方法 连续收集2010年我国六家医院分离的22株宋内志贺菌,采用纸片扩散法测定其对抗菌药物的敏感性.采用脉冲场凝胶电泳(PFGE)进行分子同源性检测,PCR-限制性片段长度多态性(RFLP)进行整合子检测及分类,联合RFLP和DNA测序技术分析整合子携带的耐药基因.结果 宋内志贺菌多重耐药率高达90.9％ (20/22),对四环素和复方磺胺甲噁唑耐药率最高,为95.5％,对青霉素类抗生素(氨苄西林、哌拉西林、阿莫西林)也呈高水平耐药,耐药率分别为86.4％,90.9％和90.9％.PFGE聚类分析结果显示,22株宋内志贺菌可分为10种PFGE亚型,且均属于同一群,其中优势型为F6型,在济南、长春和上海三市传播.59.1％(13/22)的宋内志贺菌中检出Ⅰ类整合子,其中7株Ⅰ类整合子阳性菌株可变区扩增阳性;86.4％(19/22)的宋内志贺菌检出Ⅱ类整合子,Ⅱ类整合子可变区扩增全部阳性;未检测到Ⅲ类整合子.22株宋内志贺菌中仅有1株(4.5％)检测到非典型Ⅰ类整合子,其可变区扩增亦阳性.DNA测序发现Ⅰ类整合子中携带耐药基因盒dfrA17-aadA5,Ⅱ类和非典型Ⅰ类整合子可变区分别携带耐药基因盒dfrA1-sat1-aadA1和bla oxa-30-aadA1.结论 多重耐药宋内志贺菌在我国不同地区间传播,整合子在宋内志贺菌中广泛存在,参与多重耐药的形成.

abstractsObjective To investigate the homology of Shigella sonnei from different regions of China,and to study the mechanism of drug-resistance mediated by integron.Methods A total of 22 strains of Shigella sonnei isolated from six hospitals of China in 2010 were collected.The antibiotic susceptibility was tested by disk diffusion method.The molecular homology was analyzed by pulsed field gel electrophoresis (PFGE).The classification of integrons was performed by analyzing the positive PCR products using restriction fragment length polymorphism (RFLP).RFLP and DNA sequencing were used to analyze the resistance genes in integrons.Results Multiple resistance was detected in 20 (90.9％) Shigella sonnei strains.The highest resistant rates were to tetracycline and compound sulfamethoxazole (95.5％),and the resistant rates to ampicillin,piperacillin and amoxicillin were 86.4％,90.9％ and 90.9％,respectively.PFGE cluster analysis showed that 22 strains of Shigella sonnei might be divided into 10 PFGE subtypes,and all belonged to the same group.F6 was the predominant subtype,and was prevalent in Jinan,Changchun and Shanghai.59.1％ 13/22) strains were shown to be class Ⅰ integron positive,in which 7 strains contained cassette regions; 86.4％ (19/22)strains were shown to be class Ⅱ integron positive,all of them were also positive for cassette regions; and no class Ⅲ integron was detected.The atypical class Ⅰ integron was detected in only 1 (4.5％) strain,and it was positive for cassette regions.The cassette arrays dfrA17-aadA5 of class Ⅰ integron,dfrA1-sat1-aadA1 of class Ⅱ integron,and blaoxa-30-aadA1 of atypical class Ⅰ integron were identified.Conclusions Multiple resistant Shigella sonnei exists in different regions of China.Integrons are widespread in Shigella sonnei and mediate the emergence of multiple resistant Shigella sonnei.